<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
       #sf{color: red}/*id选择器*/
        .c1{color: blue}/*class选择器*/
        #sf,h3{background-color: black}/*分组选择器*/
        [type]{color: red}/*包含type属性的元素*/
        [type="text"]{background-color: antiquewhite}
        /*任意元素选择器*/
        *{
            /*边框:边框粗细 实线边框 边框颜色*/
            border: 1px solid purple;
        }
    </style>
</head>
<body>
<input type="text">
<input type="password">
<h1 id="sf">张三丰</h1>
<h1>张翠山</h1>
<h1 class="c1">张无忌</h1>
<div>div1</div>
<div class="c1">div2</div>
<div>div3</div>
<h3 class="c1">我是👁</h3>
</body>
</html>